Referring to FIGS. 1, 2a, 2b, and 3, an illustrative embodiment of a conventional code division multiple access/high data rate (CDMA/HDR) communication network 10 may include a packet data service node (PDSN) 12 that is operably coupled to the Internet 14 and a base station controller (BSC) 16 that is operably coupled to access points (APs) 18a, 18b, and 18c. Access terminals (ATs) 20a, 20b, and 20c in turn may be operably coupled to one or more of the APs 18a, 18b, and 18c. 
As will be recognized by persons having ordinary skill in the art, a CDMA/HDR communication network typically utilizes a combination of time division multiple access (TDMA) and CDMA. In an illustrative embodiment, each communication channel is shared among several users, but on an as-needed basis rather than a fixed time slot as in TDMA. An example of a CDMA/HDR communications network is the wireless communication network available from Qualcomm, Inc. that, in an illustrative embodiment, provides a 2.4 Mbps data rate in a standard 1.25 MHZ CDMA bandwidth.
During operation of the network 10, in an illustrative embodiment, an active set 22 of APs may communicate with the AT 20a utilizing a wireless forward communication link 24 and a wireless reverse communication link 26. In an illustrative embodiment, at any given time period, only one of the APs in the active set 22 may communicate with the AT 20a in the forward communication link 24. By contrast, in the reverse communication link 26, the AT 20a may communicate with one or more of the APs in the active set 22.
Furthermore, during operation of the network 10, in an illustrative embodiment, in the forward communication link 24, the APs 18 may transmit a power control signal, a pilot signal, and/or a data payload to the ATs 20 using a power control channel 24a, a pilot channel 24b, and/or a data payload channel 24c, respectively. In an illustrative embodiment, the power control signal controls the power of the signals transmitted by the corresponding AT 20. Thus, in this manner, the power level of signals transmitted by a particular AT 20 is controlled by one or more of the APs 18. In an illustrative embodiment, in the reverse communication link 26, the ATs 20 may transmit data rate control signals to the APs 18 using a data rate control channel 26a. In an illustrative embodiment, the data rate control signal controls the maximum rate of data transmitted by the corresponding AP 18 to a particular AT 20 as a function of the carrier to interference ratio (C/I) for the pilot signal transmitted by the corresponding AP to the particular AT. Thus, in this manner, the maximum rate of data transmission from a particular AP 18 to a particular AT 20 is controlled as a function of the calculated C/I for the pilot signal that was transmitted from the particular AP 18 to the particular AT 20.
In a typical CDMA/HDR network, as illustrated in FIG. 3, the AP 18a may service a plurality of ATs, 20a and 20b. Conventional methods of scheduling the transmission of data from the AP 18a to the ATs, 20a and 20b, utilize a proportional fairness criteria in which a proportional fairness index is calculated for each forward communication link between the AP and the ATs. The proportional fairness index is typically calculated by dividing the peak data transmission rate by the historical average data transmission rate for some predetermined time period for each of the forward communication links between the AP 18a and the ATs, 20a and 20b. The peak data transmission rate is typically equated to the maximum data transmission rate value generated by the ATs, 20a and 20b, as a function of the calculated C/I for the forward communications link and transmitted by the ATs to the AP 18a using the data rate control signal. The AP 18a may then transmit data to the ATs, 20a and 20b, based upon the proportional fairness index values calculated for each forward communication link. Typically, the AP 18a may then schedule transmission of data within an available time slot to the AT having the highest proportional fairness index.
The scheduling of data transmission provided by using the proportional fairness criteria suffers from a number of drawbacks. For example, the proportional fairness criteria does not work very well when not enough data is in the queue to fully utilize the available physical packet layer size. This could happen, for example, when there is a low data transmission rate at the traffic origination point or a bottleneck in the network, or where the data being transmitted is the remaining small amount of a data burst.
The present invention is directed to improving the scheduling of data transmissions in the forward communication links in CDMA/HDR communication networks.